How to read a Ward Labs water report
A Ward Labs report is the standard first step into water chemistry for US homebrewers: one small bottle mailed in, a full breakdown of ions and pH mailed back. Most of those numbers drop straight into a calculator, but two of them carry gotchas that can ruin brewing water if you miss them.
The fields that matter
- Calcium (Ca) and Magnesium (Mg) · reported directly in ppm. Enter as-is. Calcium is your yeast-health and clarity mineral (50–150 ppm is the usual brewing range); magnesium above ~30 ppm starts tasting harsh.
- Sodium (Na) and Chloride (Cl) · direct ppm, enter as-is. Chloride rounds and fills; sodium adds fullness in moderation.
- Sulfate, reported as SO₄-S. Gotcha number one. Ward reports sulfur, not sulfate: multiply by 3 to get the sulfate concentration every brewing calculator expects. A report reading “SO4-S 14” means 42 ppm sulfate. Miss this and every sulfate decision you make will be 3× off.
- Total Alkalinity, CaCO₃. Gotcha number two. This is not bicarbonate; it's the water's buffering capacity expressed in calcium-carbonate equivalents. For water below pH 9, bicarbonate ≈ alkalinity × 1.22 (the converter tool does the exact split at your water's pH). Alkalinity is the single most consequential number on the report: it's what fights you when brewing pale beer.
- pH · enter as reported. It barely affects the mash directly, but the carbonate math uses it as the starting point.
- Nitrate, reported as NO₃-N · not used in the calculator. It doesn't affect brewing chemistry at potable levels; it's a water-safety indicator.
The fields you can (mostly) ignore
Total dissolved solids, conductivity, and total hardness are all derived summaries of the ions above: useful as cross-checks, not inputs. Potassium and iron matter only when elevated: iron above ~0.3 ppm can taste metallic and is worth fixing at the filter, not the mash. “Cation/anion balance” tells you whether the lab's numbers are internally consistent (a difference under 0.5 meq/L is fine).
Entering it into brewwtr
Open the calculator, expand Source water, and type the six main ions, remembering the ×3 on sulfate and converting alkalinity to bicarbonate. The app recomputes alkalinity, hardness, and residual alkalinity instantly and flags any ion imbalance, which catches most transcription mistakes. From there, pick a target profile and let the calculator work out the additions.
FAQ
Which Ward Labs test should brewers order?
The Household Mineral Test (W-6). It covers every ion brewing chemistry needs (calcium, magnesium, sodium, sulfate, chloride, alkalinity, and pH) for around the price of a sack of grain.
How often should I retest my water?
Once is enough to start; retest if your supply changes seasonally (common with surface water) or your utility switches sources. Brewers on wells should consider testing across seasons once.
Can I just use my utility’s annual water quality report?
Sometimes. Utility reports focus on safety, not brewing: they often omit sulfate or chloride, report wide ranges rather than numbers, and may blend sources. A lab test of the water at your tap removes the guessing.
brewwtr is independent of Ward Laboratories; they're simply the lab most US homebrewers use. Unit conversions follow standard water chemistry practice; see A.J. deLange, “Understanding Alkalinity and Hardness,” for the full treatment of the CaCO₃ convention.